This invention relates to the construction of dosaging valves in general and, in particular, to a new and useful diaphragm for a breath-controlled dosaging valve in gas masks and respirators.
Breath-controlled dosaging valves are used in gas maks and respirators. Gas masks protect the wearer against harmful admixtures and lack of oxygen in the air to be inhaled. Respirators serve to enhance breathing or to provide a substitute in case breathing is reduced or stops.
An essential element is a diaphragm which transforms pressure variations into control movements. It is admitted on one side by the possibly aggressively contaminated surrounding atmosphere and, on the inside, by the breathing gas to be controlled. The diaphragm must perform its function within the possible temperature limits of -70.degree. C. to +80.degree. C. This takes into account the fact that the expansion of the breathing gas leads to greater cooling than that corresponding to the ambient temperature. A known pressure gas mask, which is used particularly for gas protection and diving, is equipped with a lung-controlled air supply. In this apparatus, a pressure-sensitive control element with a diaphragm is connected to the breathing gas pipe, which opens or closes the pressure gas supply valve automatically at a certain pressure. The diaphragm shuts off a housing through which the pressure gas current to be inhaled is conducted.
In the center of the diaphragm, a lever is arranged, which is mounted in a bearing inside of the housing. Another lever, which actuates the valve leading to the pressure gas supply bears against this lever. In order to protect the diaphragm against the environment, it is provided with a cover. Bores in the cover establish the pressure connections to the surrounding atmosphere.
The diaphragm moves with the pressure difference between the surrounding air and the pressure in the breathing hose, and thus controls the sealing valve over the levers. The diaphragm is exposed on one side to the possibly aggressively contaminated outside air and, on the other side, to the pressure gas. Data concerning the material of the diaphragm are not given. According to the drawing, it is a one-layer diaphragm. The said diaphragm cannot withstand the aggressiveness of the surrounding atmosphere for too long. In addition, the impermeability to gas is insufficient. The entrained breathing gas supply is thus unnecessarily stressed (See German Pat. No. 959,620.).